1. Field of the Invention
This invention is directed for use in conjunction with equipment for closing or sealing containers such as bags, boxes, or the like. Generally speaking, after the container has been sealed closed it is necessary or desirable to imprint information across or near the sealed edge. This is done with a device called a printing coder. For continuous and automatic action, the coder is preferrably in wheel or cylindrical form with the printing type mounted on the outside of the cylinder or wheel.
2. Description of the Prior Art
A variety of printing coders have been used in the past. One of these is a printing cylinder in which a rubber sheet is adhesively attached to the outer surface of a cylinder. The type font is inserted in grooves or slots on the outer face of the rubber sheet. This has a decided drawback when the printer is used in conjunction with other machinery because the print type has a tendency to work loose because of the vibration of the equipment and the speed of rotation of the coder cylinder.
Another prior art device is shown in U.S. Pat. No. 2,874,637 and consists of a wire coil mounted on the outside of a cylinder with the spaces between the coil windings being used to hold the type print in place. This device also suffers in its ability to securely hold the type under vibration. Also, if the coils are spaced close enough to try to hold the type tightly, then it may be difficult to remove the type to insert new type print.
Another prior art device is shown in U.S. Pat. No. 2,643,609. This consists of a number of rings stacked on one another to provide spaces at the outer edge of the rings for receiving the gripping or backing ribs of the printing type. In this device the spaces must be dimensioned fairly accurately to insure that when the rings are squeezed together that the ribs do not lay loosely in the spaces between the rings. Another difficulty with the latter device is that the rings have to be separated or pushed apart in order to insert the ribs. This is especially difficult in the case of a large diameter printing wheel where the rings might be as large as 71/2 inches in diameter.